Cod sursa(job #2756684)

Utilizator rapidu36Victor Manz rapidu36 Data 2 iunie 2021 12:19:58
Problema Invers modular Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.89 kb
#include <fstream>

using namespace std;

int euler(int n)
{
    int d = 2, e = n;
    while (d * d <= n)
    {
        if (n % d == 0)
        {
            e = e / d * (d - 1);
            while (n % d == 0)
            {
                n /= d;
            }
        }
        d++;
    }
    if (n != 1)
    {
        e = e / n * (n - 1);
    }
    return e;
}

int putere(int a, int n, int m)
{
    ///calculeaza a la n modulo m
    int p = 1;
    while (n != 0)
    {
        if ( n % 2 != 0)
        {
            p = (long long)p * a % m;
        }
        a = (long long)a * a % m;
        n /= 2;
    }
    return p;
}

int main()
{
    ifstream in("inversmodular.in");
    ofstream out("inversmodular.out");
    int a, n;
    in >> a >> n;
    int phi = euler(n);
    out << putere(a, phi - 1, n);
    in.close();
    out.close();
    return 0;
}